The neuropsychology of mania is not well understood. Although patients with mania generally perform more poorly on tests of attention, memory, verbal and spatial perception, motor coordination, problem solving, and distractibility, it is unclear whether these deficits represent state- dependent or trait-specific factors. This is particularly relevant in distinguishing between the pattern of attentional deficits in mania and other disorders. For example, attentional impairment is thought to be trait-specific in schizophrenia since it appears during both acute and remitted states, while in mania, this deficit may be present only during the acute phase of illness and is therefore state-dependent. However, in previous studies, variability in the clinical severity of mania, medication status, and illness chronicity limit the interpretation of results. One way to address these issues is to test patients hospitalized for a first manic episode while in an acute state, and over the course of treatment. Hence, the objective of this study is to examine attentional functioning during the early course of treatment in patients hospitalized for a first manic episode to determine whether deficits represent state-or trait-dependent factors. A second objective of this study is to clarify the temporal relationship between treatment and the hypothesized attentional abnormalities and symptom expression. To achieve this objectives, we will test the following hypotheses: 1). Subjects hospitalized for a first manic episode will exhibit greater attentional impairment than a group of stable, medicated outpatients with mania, and normal controls, with significant improvement over 3 subsequent test sessions occurs at discharge, one week later, and one month later. 2). Attentional improvement will correlate with symptomatic improvement, particularly manic symptoms. In addition, we will attempt to replicate findings in schizophrenia demonstrating that changes in attentional functioning precede and predict symptomatic changes.